I am surprised that no one has built this functionality into their processors, I would have thought it would be basic functionality.

Well, it may be basic to you, but apparently the FO designers
deemed it to be more of a fringe case (along with features
like the possibility to retrieve the actual number of pages
in a document rather than the representation of the page number
of the last page, and others).
BTW FOP 0.20.5 had an (poorly documented) extension function for
defining a table footer which was printed only at page breaks,
which achieved the effect for tables, and by using a blind table
for most other content. IIRC other FO processors also have
similar extensions.